386 
Argas persicus 
of the body. In the Txodid ticks their place is taken by the well-known 
integumental grooves. The arrangement of the discs is defined abso¬ 
lutely by the muscular system, just as Donitz has shown 1 to be tbe case 
Fig. 2. Fig. 3. 
Fig. 2. Argas persicus ? . Diagram showing the distribution and muscle relationship 
of the discs, on the dorsal surface of the body. The associations of the discs with 
their corresponding muscles are indicated by the various shadings—marginal, postero¬ 
median and postero-aecessory dorso-ventral body-muscles— black; abductors of the 
coxae— horizontal line shading; adductors of the coxae— vertical line shading; 
dorso-genital muscles— inclined line shading; depressor and levator muscles of the 
capitulum— stippled shading ; retractor muscles of the chelicerae— xohite. 
Fig. 3. Argas persicus ? . Diagram showing distribution of the discs on the ventral 
surface of the body. 
1 Donitz, W. (1909), pp. 440-442. 
